Optimization of BOFS high-gravity carbonation technology: Consideration of theoretical guidance for up-scaling applications

This study investigated the high-gravity (higee) carbonation reaction of a basic oxygen furnace slag (BOFS)-water-CO2 three-phase system via a rotating packed bed (RPB). The effect of different carbonation conditions on the higee carbonation process was explored. To achieve enhanced mass transfer, energy savings, and cost-effectiveness, this study aimed to optimize parameters such as BOFS component, acceleration, gas-liquid velocity ratio, and gas flow rate. Comparative analysis revealed that portlandite-rich BOFS exhibited a significantly higher Ca conversion ratio (2.1 times) and mass transfer coefficient values (KGαe) (5.5 times) than calcium silicate-rich BOFS. Systematic graphical presentation identified an acceleration of 430 m/s2, a gas-liquid velocity ratio of 25–30, and a gas velocity to RPB volume range of 4.7–6.6 min−1 as the optimal operating conditions for high KGαe (>0.2 s−1) and low energy consumption (144–151 kWh/t-CO2). Furthermore, prolonged RPB operation led to a 1.5-fold reduction in mass transfer performance, but reducing the liquid-to-solid ratio was a cost-effective measure to compensate for efficiency losses. The estimated cost for the higee carbonation process ranged from 106 to 111 CNY/t-CO2. These findings can provide valuable insights and practical recommendations for the industrial application of the higee carbonation technology in steel-making plants. [Display omitted] •Carbonation reaction in BOFS-water-CO2 ternary system was elucidated.•Portlandite-rich BOFS demonstrates higher carbonation and mass transfer efficiency.•BOFS coverage on packing reduces carbonation efficiency by 1.5 times.•Reducing solid-liquid ratio is more cost-effective than replacing packing material.